Process for the removal of phosphorus from manganese ores



Patented July 29, 1941 PROCESS FOR. THE REMOVAL OF PHOS- PHORUS FROM MANGANESE ORES Troy w. Carney, Fort Smith, Ark.

No Drawing. Application October 25, 1940,

Serial No. 362,788

4 Claims.

This invention relates to new and useful improvements in a process for the removal of phosphorus from manganese ores.

Essentially, the process consists in igniting a manganese oxide ore (tervalent or tetravalent manganese oxide or hydrated oxides) with a manganese sulphate, all in a finely ground condition, at a temperature sufiicient to decompose the sulphate and drive oif the sulphur trioxide ($03), after which the calcined ore is extracted with water 'or with a dilute aqueous solution of an acid.

Numerous processes have been invented for the removal of phosphorus from manganese ores, but none of these processes have met with commercial success because of inherent deficiencies. Such prior processes included subjecting the ore to a reducing gas, which is not a practical proposition. The atmosphere used in the present invention is strong oxidizing and depends on an. entirely different principle. Another prior proposal consisted in vaporizing the phosphorus in a. furnace and involved the reduction of the ore, in part at least, to the metallic state. This "also is not a practical method.

Other methods have also been proposed but in each instance there was some lack which prevented its adoption by the industry.

In accordance with this invention the man-- ganese sulphate maybe added as such, or formed. in situ by adding to the ore sulphuric acid, sulphurous acid, $02 or free sulphur, the last forminga manganese sulphate or sulphates on ignition. Other sulphates may be used; in fact any sulphate which decomposes with liberation of sulphur trioxide when heated to the temperature in use. It should be clearly understood that this invention is not limited as to the means of introduction of the sulphate radicaL- A typical procedure will now be given which constitutes a practical working formula but which may be varied both qualitatively and quantitatively through an infinite number of modifications.

100 parts by weight of an ore, such as psilomelane (ground to pass a 100 mesh screen) is moistened with water containing sulphuric acid equivalent to about 2% of the weightof the ore taken. This is dried by gentle heat, and broken into lumps about the size of an egg. These lumps are then charged into a rotary kiln, reverberatory furnace or crucible and strongly ignited at near 950 degrees centigrade for a period of time sufllcient to thoroughly drive off all the sulphur trloxide (except for traces). It is essential to avoid a reducing atmosphere during the ignition,

operating preferably with an oxidizing atmos-' phere with a very gentle ventilation.

After ignition the ore is cooled and re-ground, or rather, the lumps are broken down into powder by some form of disintegrating equipment. This powder is mixed intimately with water or dilute acid, preferably nitric. 'If acid is used,

it is preferable to use just suflicient an amount to maintain an acid reaction toward Congo red during the leaching and filtration. The product is then filtered and washed, the greater part of the phosphorus going out in the liquid.

While I have described the preferred embodi-' ments of my invention, it is to be understood that I do not limit myself to the precise constructions herein disclosed and the right is reserved to all changes and modifications.

Having thus described my invention, what I claim as new and desire to secure by United States Letters Patent is:

l. A process for removal of phosphorus from manganese ores, consisting in igniting a manganese oxide ore with a manganese sulphate, all

in finely ground condition, at a temperature sufficient to decompose the sulphate and drive off sulphur trioxide, after which the calcined ore is extracted with water.

2. A process for removal of phosphorus from manganese ores, consisting in igniting a manga- 1 nese oxide ore with a manganese sulphate, all in finely ground condition, at a temperature suflicient to decompose the sulphate and drive off sulphur trioxide, after which the calcined ore is extracted with a dilute aqueous solution of an acid.

3. A process for the removal of phosphorus I from manganese ores, consisting in igniting a manganese oxide ore with a manganese sulphate formed in situ by adding to the ore a sulphate radical, at a temperature suflicient to decompose 

